26-80
Catalyst 3750 Metro Switch Software Configuration Guide
78-15870-01
Chapter 26 Configuring QoS
Configuring Hierarchical QoS
This example shows how to create a VLAN-level class-map for 802.1Q tunneling called dot1q, which
matches all traffic with an outer VLAN ID of 5 and an inner VLAN ID of 3 to 8:
Switch(config)# class-map match-all dot1q
Switch(config-cmap)# match vlan 5
Switch(config-cmap)# match vlan inner 3 - 8
This example shows how to create a VLAN-level class-map called vlan203, which matches traffic in
VLAN 203:
Switch(config)# class-map match-all vlan203
Switch(config-cmap)# match vlan 203
Configuring an Egress Two-Rate Traffic Policer
You can configure a two-rate traffic policer within a policy map at the class level, at the VLAN level,
and at the physical level by using the police cir or the police cir percent policy-map class configuration
command. At the physical level of the hierarchy, you can police only the class-default class in an egress
policy attached to an ES port.
The policer limits the transmission rate of a traffic class and marks actions (conform, exceed, and
violate) for each packet. Within the conform, exceed, and violate categories, you decide packet
treatments. In the most common configurations, you configure packets that conform to be sent, packets
that exceed to be sent with a decreased priority, and packets that violate to be dropped. You can decrease
the priority of the CoS, the DSCP, the IP precedence, or the MPLS EXP bits in the packet. You configure
the policer by using the police cir policy-map class configuration command.
You also can use the police cir percent policy-map class configuration command to configure an egress
traffic policer that uses two rates, the CIR and the PIR. The switch calculates the CIR and PIR based on
a percentage of the maximum amount of bandwidth assigned to the parent class. The maximum
bandwidth is controlled by the shape policy-map class configuration command if it is configured.
Otherwise, the maximum bandwidth is the physical port bandwidth (1 Gbps). For more information
about the interaction between the police cir percent command and the shape command, refer to the
police cir percent command in the command reference for this release.
Before beginning this procedure, make sure that you have created the class map to isolate traffic. For
more information, see the “Classifying Egress Traffic by Using Class Maps” section on page 26-78.
Beginning in privileged EXEC mode, follow these steps to configure a class-level, two-rate traffic
policer in a service policy for outbound traffic. This procedure is optional. The examples that follow the
procedure show how to configure a class-level, a VLAN-level, and a physical-level policer.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
policy-map policy-map-name Create a policy map by entering the policy-map name, and enter
policy-map configuration mode.
By default, no policy maps are defined.
Step 3
class class-name Specify the name of the class whose traffic policy you want to create
or change, and enter policy-map class configuration mode.
By default, no traffic classes are defined.
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